Movable barrier operators generally serve to selectively move a movable barrier (such as a segmented or one-piece garage door, swinging gate, sliding gate, rolling shutter, and so forth) between an opened and a closed position using one or more motors. It is known to use safe-operation devices to detect an obstacle in the path of the moving barrier (particularly when the moving barrier moves to a closed position) through use of light, sound, radio-frequency, and/or contact sensing mechanisms. Upon sensing an obstacle, the safe-operation device provides a signal that can be used by the movable barrier operator accordingly to aid in avoiding potentially harmful contact between the movable barrier and the detected obstacle. For example, the movable barrier operator may respond by preventing barrier movement or stopping and/or reversing barrier movement. These safe-operation devices aid in ensuring that the movable barrier can be moved without undue risk to persons or property in the immediate vicinity.
One example of a safe-operation device is a photobeam system. Generally speaking, these photobeam systems include an emitter and a receiver. In “thru-beam” systems, the emitter and the receiver are disposed on opposite sides of the movable barrier. In “retro-reflective” systems, the emitter and the receiver are disposed on the same side of the movable barrier with the opposing side having a reflective surface that reflects the emitted signal back to the receiver.
The components of a photobeam system are generally disposed near the ground and the path of travel of the movable barrier. These systems are designed with a narrow angle of transmission (for example, approximately two degrees) between the emitter and the receiver. This narrow transmission angle serves to reduce the possibility of the receiver receiving signals that have reflected off of a nearby object or surface. Such reflected signals may interfere with proper detection of the presence of an obstacle.
The narrow angle of transmission required by previous photobeam systems raises several problems. For example, such systems require precise placement of the photobeam components to allow the signal to be properly received by the receiver. As such, the installation of these components may be time consuming and difficult for both end users and professional installers. Furthermore, even the slightest contact to a photobeam component on either side of the movable barrier can knock the system out of alignment.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein. Furthermore, descriptions used throughout the disclosure herein can have a variety of suitable meanings. For example, the phrase “obstacle detection system” as used herein may refer to an object detector or detection system, and may refer to a photobeam apparatus or photobeam system.